The present invention relates to a rod-shaped antenna provided for vehicles such as automobiles and, more particularly, to a rod-shaped automobile antenna having a means for eliminating a whistling sound generated during the vehicle driving operation.
A rod-shaped antenna, which is constituted of an antenna element of a rod-shaped conductor, has been widely used for vehicles such as automobiles. This rod-shaped antenna generates a so-called whistling sound when an automobile runs at high speed or when the running automobile is exposed to a strong wind. Not a little, the whistling sound makes the occupants of the automobile uncomfortable. Various measures have been so far taken to eliminate the whistling sound.
Jpn. Utility Model Appln. KOKAI Publication No. 53-17136 discloses an automobile pole antenna having a whistling sound reduction means. This antenna is constituted by slidably joining conductive pipes of different diameters to each other, and a spiral wire is wounded on the outer circumference of the first element (conductive pipe). The above publication also discloses a pole antenna wherein a groove is formed circularly or spirally in the first element and a spiral wire is wounded on the groove.
The above automobile pole antenna has a drawback wherein a whistling sound cannot be eliminated so greatly though its structure is relatively complicated.